NEURAL CIRCUITS OF SENSATION AND MEMORY

Research

Sensation and memory are tightly linked in our everyday lives. Meaningful sensory experiences can transform to become long-term memories, and memories of past experiences influence how we process and perceive incoming sensory input. This bidirectional interaction between sensation and memory is a key process in healthy everyday life, and its failure is found in conditions such as post-traumatic stress disorder (PTSD), dementia, and schizophrenia. Our lab aims to understand the neural circuit mechanisms that underlie the bidirectional interaction between sensation and memory in health and disease.

To pursue these questions, our core experimental approach is to record and manipulate neural activity simultaneously from multiple brain regions involved in both sensory coding and memory processes, while rodents perform sensory- and memory- guided tasks. One brain region of interest in the lab is the auditory cortex, which is strongly involved in processing of sounds. By monitoring neural activity in the auditory cortex as the animal is engaged in task performance and during subsequent sleep, we can tap into the sensory neural representation that salient sounds leave during and following experience. To track how some of these sensory representations subsequently assimilate into long-term memories, we simultaneously record neural activity in the hippocampus. The hippocampus is critical for forming new episodic memories, and exhibits reactivation of neural activity patterns of past experiences, a phenomenon believed to support memory consolidation. By simultaneously monitoring and manipulating neural activity in the auditory cortex and hippocampus across learning, our lab aims to understand how information processing within each of these brain regions, as well as communication between them, underlies diverse cognitive phenomena linking sensation and memory.

To pursue this line of research we use a wide range of neurophysiological and optical techniques to record and perturb population neural activity patterns in the neocortex and hippocampus of rodents. We perform multi-tetrode electrophysiological recordings, two-photon calcium imaging and optogenetic manipulations as rodents learn to perform sensory- and memory- guided tasks. Closed-loop experiments allow us to identify specific neural activity patterns in real time and use them as triggers for neural or sensory stimulation. We carry out computational analyses to identify the underlying neural population activity patterns. Using these methods, we aim to form a link between detailed and well-defined activity patterns of neuronal populations to cognitive phenomena of sensation and memory.

Z-Stack of mouse auditory cortex imaged with a two-photon microscope, going from the surface of the brain to about 450 micrometers deep. Neurons in layers 2/3 are loaded with a calcium indicator (Fluo-4) in green, and astrocytes in red (SR101).

Top-down view of a rat walking along a track as part of a sound- and memory- guided task. Different hippocampal place cells (area CA1) fire spikes in specific locations along the path. At the end of the trajectory, as the rat is consuming reward, two population activity bursts (candidate replay event) occur during sharp-wave ripple events.